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Linux/net/netfilter/ipvs/ip_vs_proto_tcp.c

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  1 /*
  2  * ip_vs_proto_tcp.c:   TCP load balancing support for IPVS
  3  *
  4  * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
  5  *              Julian Anastasov <ja@ssi.bg>
  6  *
  7  *              This program is free software; you can redistribute it and/or
  8  *              modify it under the terms of the GNU General Public License
  9  *              as published by the Free Software Foundation; either version
 10  *              2 of the License, or (at your option) any later version.
 11  *
 12  * Changes:
 13  *
 14  */
 15 
 16 #define KMSG_COMPONENT "IPVS"
 17 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 18 
 19 #include <linux/kernel.h>
 20 #include <linux/ip.h>
 21 #include <linux/tcp.h>                  /* for tcphdr */
 22 #include <net/ip.h>
 23 #include <net/tcp.h>                    /* for csum_tcpudp_magic */
 24 #include <net/ip6_checksum.h>
 25 #include <linux/netfilter.h>
 26 #include <linux/netfilter_ipv4.h>
 27 
 28 #include <net/ip_vs.h>
 29 
 30 
 31 static struct ip_vs_conn *
 32 tcp_conn_in_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
 33                 const struct ip_vs_iphdr *iph, unsigned int proto_off,
 34                 int inverse)
 35 {
 36         __be16 _ports[2], *pptr;
 37 
 38         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
 39         if (pptr == NULL)
 40                 return NULL;
 41 
 42         if (likely(!inverse)) {
 43                 return ip_vs_conn_in_get(af, iph->protocol,
 44                                          &iph->saddr, pptr[0],
 45                                          &iph->daddr, pptr[1]);
 46         } else {
 47                 return ip_vs_conn_in_get(af, iph->protocol,
 48                                          &iph->daddr, pptr[1],
 49                                          &iph->saddr, pptr[0]);
 50         }
 51 }
 52 
 53 static struct ip_vs_conn *
 54 tcp_conn_out_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
 55                  const struct ip_vs_iphdr *iph, unsigned int proto_off,
 56                  int inverse)
 57 {
 58         __be16 _ports[2], *pptr;
 59 
 60         pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
 61         if (pptr == NULL)
 62                 return NULL;
 63 
 64         if (likely(!inverse)) {
 65                 return ip_vs_conn_out_get(af, iph->protocol,
 66                                           &iph->saddr, pptr[0],
 67                                           &iph->daddr, pptr[1]);
 68         } else {
 69                 return ip_vs_conn_out_get(af, iph->protocol,
 70                                           &iph->daddr, pptr[1],
 71                                           &iph->saddr, pptr[0]);
 72         }
 73 }
 74 
 75 
 76 static int
 77 tcp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
 78                   int *verdict, struct ip_vs_conn **cpp)
 79 {
 80         struct ip_vs_service *svc;
 81         struct tcphdr _tcph, *th;
 82         struct ip_vs_iphdr iph;
 83 
 84         ip_vs_fill_iphdr(af, skb_network_header(skb), &iph);
 85 
 86         th = skb_header_pointer(skb, iph.len, sizeof(_tcph), &_tcph);
 87         if (th == NULL) {
 88                 *verdict = NF_DROP;
 89                 return 0;
 90         }
 91 
 92         if (th->syn &&
 93             (svc = ip_vs_service_get(af, skb->mark, iph.protocol, &iph.daddr,
 94                                      th->dest))) {
 95                 if (ip_vs_todrop()) {
 96                         /*
 97                          * It seems that we are very loaded.
 98                          * We have to drop this packet :(
 99                          */
100                         ip_vs_service_put(svc);
101                         *verdict = NF_DROP;
102                         return 0;
103                 }
104 
105                 /*
106                  * Let the virtual server select a real server for the
107                  * incoming connection, and create a connection entry.
108                  */
109                 *cpp = ip_vs_schedule(svc, skb);
110                 if (!*cpp) {
111                         *verdict = ip_vs_leave(svc, skb, pp);
112                         return 0;
113                 }
114                 ip_vs_service_put(svc);
115         }
116         return 1;
117 }
118 
119 
120 static inline void
121 tcp_fast_csum_update(int af, struct tcphdr *tcph,
122                      const union nf_inet_addr *oldip,
123                      const union nf_inet_addr *newip,
124                      __be16 oldport, __be16 newport)
125 {
126 #ifdef CONFIG_IP_VS_IPV6
127         if (af == AF_INET6)
128                 tcph->check =
129                         csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
130                                          ip_vs_check_diff2(oldport, newport,
131                                                 ~csum_unfold(tcph->check))));
132         else
133 #endif
134         tcph->check =
135                 csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
136                                  ip_vs_check_diff2(oldport, newport,
137                                                 ~csum_unfold(tcph->check))));
138 }
139 
140 
141 static inline void
142 tcp_partial_csum_update(int af, struct tcphdr *tcph,
143                      const union nf_inet_addr *oldip,
144                      const union nf_inet_addr *newip,
145                      __be16 oldlen, __be16 newlen)
146 {
147 #ifdef CONFIG_IP_VS_IPV6
148         if (af == AF_INET6)
149                 tcph->check =
150                         ~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
151                                          ip_vs_check_diff2(oldlen, newlen,
152                                                 csum_unfold(tcph->check))));
153         else
154 #endif
155         tcph->check =
156                 ~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
157                                 ip_vs_check_diff2(oldlen, newlen,
158                                                 csum_unfold(tcph->check))));
159 }
160 
161 
162 static int
163 tcp_snat_handler(struct sk_buff *skb,
164                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
165 {
166         struct tcphdr *tcph;
167         unsigned int tcphoff;
168         int oldlen;
169 
170 #ifdef CONFIG_IP_VS_IPV6
171         if (cp->af == AF_INET6)
172                 tcphoff = sizeof(struct ipv6hdr);
173         else
174 #endif
175                 tcphoff = ip_hdrlen(skb);
176         oldlen = skb->len - tcphoff;
177 
178         /* csum_check requires unshared skb */
179         if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
180                 return 0;
181 
182         if (unlikely(cp->app != NULL)) {
183                 /* Some checks before mangling */
184                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
185                         return 0;
186 
187                 /* Call application helper if needed */
188                 if (!ip_vs_app_pkt_out(cp, skb))
189                         return 0;
190         }
191 
192         tcph = (void *)skb_network_header(skb) + tcphoff;
193         tcph->source = cp->vport;
194 
195         /* Adjust TCP checksums */
196         if (skb->ip_summed == CHECKSUM_PARTIAL) {
197                 tcp_partial_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
198                                         htons(oldlen),
199                                         htons(skb->len - tcphoff));
200         } else if (!cp->app) {
201                 /* Only port and addr are changed, do fast csum update */
202                 tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
203                                      cp->dport, cp->vport);
204                 if (skb->ip_summed == CHECKSUM_COMPLETE)
205                         skb->ip_summed = CHECKSUM_NONE;
206         } else {
207                 /* full checksum calculation */
208                 tcph->check = 0;
209                 skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
210 #ifdef CONFIG_IP_VS_IPV6
211                 if (cp->af == AF_INET6)
212                         tcph->check = csum_ipv6_magic(&cp->vaddr.in6,
213                                                       &cp->caddr.in6,
214                                                       skb->len - tcphoff,
215                                                       cp->protocol, skb->csum);
216                 else
217 #endif
218                         tcph->check = csum_tcpudp_magic(cp->vaddr.ip,
219                                                         cp->caddr.ip,
220                                                         skb->len - tcphoff,
221                                                         cp->protocol,
222                                                         skb->csum);
223 
224                 IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
225                           pp->name, tcph->check,
226                           (char*)&(tcph->check) - (char*)tcph);
227         }
228         return 1;
229 }
230 
231 
232 static int
233 tcp_dnat_handler(struct sk_buff *skb,
234                  struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
235 {
236         struct tcphdr *tcph;
237         unsigned int tcphoff;
238         int oldlen;
239 
240 #ifdef CONFIG_IP_VS_IPV6
241         if (cp->af == AF_INET6)
242                 tcphoff = sizeof(struct ipv6hdr);
243         else
244 #endif
245                 tcphoff = ip_hdrlen(skb);
246         oldlen = skb->len - tcphoff;
247 
248         /* csum_check requires unshared skb */
249         if (!skb_make_writable(skb, tcphoff+sizeof(*tcph)))
250                 return 0;
251 
252         if (unlikely(cp->app != NULL)) {
253                 /* Some checks before mangling */
254                 if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
255                         return 0;
256 
257                 /*
258                  *      Attempt ip_vs_app call.
259                  *      It will fix ip_vs_conn and iph ack_seq stuff
260                  */
261                 if (!ip_vs_app_pkt_in(cp, skb))
262                         return 0;
263         }
264 
265         tcph = (void *)skb_network_header(skb) + tcphoff;
266         tcph->dest = cp->dport;
267 
268         /*
269          *      Adjust TCP checksums
270          */
271         if (skb->ip_summed == CHECKSUM_PARTIAL) {
272                 tcp_partial_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
273                                         htons(oldlen),
274                                         htons(skb->len - tcphoff));
275         } else if (!cp->app) {
276                 /* Only port and addr are changed, do fast csum update */
277                 tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
278                                      cp->vport, cp->dport);
279                 if (skb->ip_summed == CHECKSUM_COMPLETE)
280                         skb->ip_summed = CHECKSUM_NONE;
281         } else {
282                 /* full checksum calculation */
283                 tcph->check = 0;
284                 skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
285 #ifdef CONFIG_IP_VS_IPV6
286                 if (cp->af == AF_INET6)
287                         tcph->check = csum_ipv6_magic(&cp->caddr.in6,
288                                                       &cp->daddr.in6,
289                                                       skb->len - tcphoff,
290                                                       cp->protocol, skb->csum);
291                 else
292 #endif
293                         tcph->check = csum_tcpudp_magic(cp->caddr.ip,
294                                                         cp->daddr.ip,
295                                                         skb->len - tcphoff,
296                                                         cp->protocol,
297                                                         skb->csum);
298                 skb->ip_summed = CHECKSUM_UNNECESSARY;
299         }
300         return 1;
301 }
302 
303 
304 static int
305 tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
306 {
307         unsigned int tcphoff;
308 
309 #ifdef CONFIG_IP_VS_IPV6
310         if (af == AF_INET6)
311                 tcphoff = sizeof(struct ipv6hdr);
312         else
313 #endif
314                 tcphoff = ip_hdrlen(skb);
315 
316         switch (skb->ip_summed) {
317         case CHECKSUM_NONE:
318                 skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0);
319         case CHECKSUM_COMPLETE:
320 #ifdef CONFIG_IP_VS_IPV6
321                 if (af == AF_INET6) {
322                         if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
323                                             &ipv6_hdr(skb)->daddr,
324                                             skb->len - tcphoff,
325                                             ipv6_hdr(skb)->nexthdr,
326                                             skb->csum)) {
327                                 IP_VS_DBG_RL_PKT(0, pp, skb, 0,
328                                                  "Failed checksum for");
329                                 return 0;
330                         }
331                 } else
332 #endif
333                         if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
334                                               ip_hdr(skb)->daddr,
335                                               skb->len - tcphoff,
336                                               ip_hdr(skb)->protocol,
337                                               skb->csum)) {
338                                 IP_VS_DBG_RL_PKT(0, pp, skb, 0,
339                                                  "Failed checksum for");
340                                 return 0;
341                         }
342                 break;
343         default:
344                 /* No need to checksum. */
345                 break;
346         }
347 
348         return 1;
349 }
350 
351 
352 #define TCP_DIR_INPUT           0
353 #define TCP_DIR_OUTPUT          4
354 #define TCP_DIR_INPUT_ONLY      8
355 
356 static const int tcp_state_off[IP_VS_DIR_LAST] = {
357         [IP_VS_DIR_INPUT]               =       TCP_DIR_INPUT,
358         [IP_VS_DIR_OUTPUT]              =       TCP_DIR_OUTPUT,
359         [IP_VS_DIR_INPUT_ONLY]          =       TCP_DIR_INPUT_ONLY,
360 };
361 
362 /*
363  *      Timeout table[state]
364  */
365 static int tcp_timeouts[IP_VS_TCP_S_LAST+1] = {
366         [IP_VS_TCP_S_NONE]              =       2*HZ,
367         [IP_VS_TCP_S_ESTABLISHED]       =       15*60*HZ,
368         [IP_VS_TCP_S_SYN_SENT]          =       2*60*HZ,
369         [IP_VS_TCP_S_SYN_RECV]          =       1*60*HZ,
370         [IP_VS_TCP_S_FIN_WAIT]          =       2*60*HZ,
371         [IP_VS_TCP_S_TIME_WAIT]         =       2*60*HZ,
372         [IP_VS_TCP_S_CLOSE]             =       10*HZ,
373         [IP_VS_TCP_S_CLOSE_WAIT]        =       60*HZ,
374         [IP_VS_TCP_S_LAST_ACK]          =       30*HZ,
375         [IP_VS_TCP_S_LISTEN]            =       2*60*HZ,
376         [IP_VS_TCP_S_SYNACK]            =       120*HZ,
377         [IP_VS_TCP_S_LAST]              =       2*HZ,
378 };
379 
380 static const char *const tcp_state_name_table[IP_VS_TCP_S_LAST+1] = {
381         [IP_VS_TCP_S_NONE]              =       "NONE",
382         [IP_VS_TCP_S_ESTABLISHED]       =       "ESTABLISHED",
383         [IP_VS_TCP_S_SYN_SENT]          =       "SYN_SENT",
384         [IP_VS_TCP_S_SYN_RECV]          =       "SYN_RECV",
385         [IP_VS_TCP_S_FIN_WAIT]          =       "FIN_WAIT",
386         [IP_VS_TCP_S_TIME_WAIT]         =       "TIME_WAIT",
387         [IP_VS_TCP_S_CLOSE]             =       "CLOSE",
388         [IP_VS_TCP_S_CLOSE_WAIT]        =       "CLOSE_WAIT",
389         [IP_VS_TCP_S_LAST_ACK]          =       "LAST_ACK",
390         [IP_VS_TCP_S_LISTEN]            =       "LISTEN",
391         [IP_VS_TCP_S_SYNACK]            =       "SYNACK",
392         [IP_VS_TCP_S_LAST]              =       "BUG!",
393 };
394 
395 #define sNO IP_VS_TCP_S_NONE
396 #define sES IP_VS_TCP_S_ESTABLISHED
397 #define sSS IP_VS_TCP_S_SYN_SENT
398 #define sSR IP_VS_TCP_S_SYN_RECV
399 #define sFW IP_VS_TCP_S_FIN_WAIT
400 #define sTW IP_VS_TCP_S_TIME_WAIT
401 #define sCL IP_VS_TCP_S_CLOSE
402 #define sCW IP_VS_TCP_S_CLOSE_WAIT
403 #define sLA IP_VS_TCP_S_LAST_ACK
404 #define sLI IP_VS_TCP_S_LISTEN
405 #define sSA IP_VS_TCP_S_SYNACK
406 
407 struct tcp_states_t {
408         int next_state[IP_VS_TCP_S_LAST];
409 };
410 
411 static const char * tcp_state_name(int state)
412 {
413         if (state >= IP_VS_TCP_S_LAST)
414                 return "ERR!";
415         return tcp_state_name_table[state] ? tcp_state_name_table[state] : "?";
416 }
417 
418 static struct tcp_states_t tcp_states [] = {
419 /*      INPUT */
420 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
421 /*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
422 /*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sTW }},
423 /*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
424 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sSR }},
425 
426 /*      OUTPUT */
427 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
428 /*syn*/ {{sSS, sES, sSS, sSR, sSS, sSS, sSS, sSS, sSS, sLI, sSR }},
429 /*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
430 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
431 /*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
432 
433 /*      INPUT-ONLY */
434 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
435 /*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSR }},
436 /*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
437 /*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
438 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
439 };
440 
441 static struct tcp_states_t tcp_states_dos [] = {
442 /*      INPUT */
443 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
444 /*syn*/ {{sSR, sES, sES, sSR, sSR, sSR, sSR, sSR, sSR, sSR, sSA }},
445 /*fin*/ {{sCL, sCW, sSS, sTW, sTW, sTW, sCL, sCW, sLA, sLI, sSA }},
446 /*ack*/ {{sCL, sES, sSS, sSR, sFW, sTW, sCL, sCW, sCL, sLI, sSA }},
447 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
448 
449 /*      OUTPUT */
450 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
451 /*syn*/ {{sSS, sES, sSS, sSA, sSS, sSS, sSS, sSS, sSS, sLI, sSA }},
452 /*fin*/ {{sTW, sFW, sSS, sTW, sFW, sTW, sCL, sTW, sLA, sLI, sTW }},
453 /*ack*/ {{sES, sES, sSS, sES, sFW, sTW, sCL, sCW, sLA, sES, sES }},
454 /*rst*/ {{sCL, sCL, sSS, sCL, sCL, sTW, sCL, sCL, sCL, sCL, sCL }},
455 
456 /*      INPUT-ONLY */
457 /*        sNO, sES, sSS, sSR, sFW, sTW, sCL, sCW, sLA, sLI, sSA */
458 /*syn*/ {{sSA, sES, sES, sSR, sSA, sSA, sSA, sSA, sSA, sSA, sSA }},
459 /*fin*/ {{sCL, sFW, sSS, sTW, sFW, sTW, sCL, sCW, sLA, sLI, sTW }},
460 /*ack*/ {{sCL, sES, sSS, sES, sFW, sTW, sCL, sCW, sCL, sLI, sES }},
461 /*rst*/ {{sCL, sCL, sCL, sSR, sCL, sCL, sCL, sCL, sLA, sLI, sCL }},
462 };
463 
464 static struct tcp_states_t *tcp_state_table = tcp_states;
465 
466 
467 static void tcp_timeout_change(struct ip_vs_protocol *pp, int flags)
468 {
469         int on = (flags & 1);           /* secure_tcp */
470 
471         /*
472         ** FIXME: change secure_tcp to independent sysctl var
473         ** or make it per-service or per-app because it is valid
474         ** for most if not for all of the applications. Something
475         ** like "capabilities" (flags) for each object.
476         */
477         tcp_state_table = (on? tcp_states_dos : tcp_states);
478 }
479 
480 static int
481 tcp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
482 {
483         return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_TCP_S_LAST,
484                                        tcp_state_name_table, sname, to);
485 }
486 
487 static inline int tcp_state_idx(struct tcphdr *th)
488 {
489         if (th->rst)
490                 return 3;
491         if (th->syn)
492                 return 0;
493         if (th->fin)
494                 return 1;
495         if (th->ack)
496                 return 2;
497         return -1;
498 }
499 
500 static inline void
501 set_tcp_state(struct ip_vs_protocol *pp, struct ip_vs_conn *cp,
502               int direction, struct tcphdr *th)
503 {
504         int state_idx;
505         int new_state = IP_VS_TCP_S_CLOSE;
506         int state_off = tcp_state_off[direction];
507 
508         /*
509          *    Update state offset to INPUT_ONLY if necessary
510          *    or delete NO_OUTPUT flag if output packet detected
511          */
512         if (cp->flags & IP_VS_CONN_F_NOOUTPUT) {
513                 if (state_off == TCP_DIR_OUTPUT)
514                         cp->flags &= ~IP_VS_CONN_F_NOOUTPUT;
515                 else
516                         state_off = TCP_DIR_INPUT_ONLY;
517         }
518 
519         if ((state_idx = tcp_state_idx(th)) < 0) {
520                 IP_VS_DBG(8, "tcp_state_idx=%d!!!\n", state_idx);
521                 goto tcp_state_out;
522         }
523 
524         new_state = tcp_state_table[state_off+state_idx].next_state[cp->state];
525 
526   tcp_state_out:
527         if (new_state != cp->state) {
528                 struct ip_vs_dest *dest = cp->dest;
529 
530                 IP_VS_DBG_BUF(8, "%s %s [%c%c%c%c] %s:%d->"
531                               "%s:%d state: %s->%s conn->refcnt:%d\n",
532                               pp->name,
533                               ((state_off == TCP_DIR_OUTPUT) ?
534                                "output " : "input "),
535                               th->syn ? 'S' : '.',
536                               th->fin ? 'F' : '.',
537                               th->ack ? 'A' : '.',
538                               th->rst ? 'R' : '.',
539                               IP_VS_DBG_ADDR(cp->af, &cp->daddr),
540                               ntohs(cp->dport),
541                               IP_VS_DBG_ADDR(cp->af, &cp->caddr),
542                               ntohs(cp->cport),
543                               tcp_state_name(cp->state),
544                               tcp_state_name(new_state),
545                               atomic_read(&cp->refcnt));
546 
547                 if (dest) {
548                         if (!(cp->flags & IP_VS_CONN_F_INACTIVE) &&
549                             (new_state != IP_VS_TCP_S_ESTABLISHED)) {
550                                 atomic_dec(&dest->activeconns);
551                                 atomic_inc(&dest->inactconns);
552                                 cp->flags |= IP_VS_CONN_F_INACTIVE;
553                         } else if ((cp->flags & IP_VS_CONN_F_INACTIVE) &&
554                                    (new_state == IP_VS_TCP_S_ESTABLISHED)) {
555                                 atomic_inc(&dest->activeconns);
556                                 atomic_dec(&dest->inactconns);
557                                 cp->flags &= ~IP_VS_CONN_F_INACTIVE;
558                         }
559                 }
560         }
561 
562         cp->timeout = pp->timeout_table[cp->state = new_state];
563 }
564 
565 
566 /*
567  *      Handle state transitions
568  */
569 static int
570 tcp_state_transition(struct ip_vs_conn *cp, int direction,
571                      const struct sk_buff *skb,
572                      struct ip_vs_protocol *pp)
573 {
574         struct tcphdr _tcph, *th;
575 
576 #ifdef CONFIG_IP_VS_IPV6
577         int ihl = cp->af == AF_INET ? ip_hdrlen(skb) : sizeof(struct ipv6hdr);
578 #else
579         int ihl = ip_hdrlen(skb);
580 #endif
581 
582         th = skb_header_pointer(skb, ihl, sizeof(_tcph), &_tcph);
583         if (th == NULL)
584                 return 0;
585 
586         spin_lock(&cp->lock);
587         set_tcp_state(pp, cp, direction, th);
588         spin_unlock(&cp->lock);
589 
590         return 1;
591 }
592 
593 
594 /*
595  *      Hash table for TCP application incarnations
596  */
597 #define TCP_APP_TAB_BITS        4
598 #define TCP_APP_TAB_SIZE        (1 << TCP_APP_TAB_BITS)
599 #define TCP_APP_TAB_MASK        (TCP_APP_TAB_SIZE - 1)
600 
601 static struct list_head tcp_apps[TCP_APP_TAB_SIZE];
602 static DEFINE_SPINLOCK(tcp_app_lock);
603 
604 static inline __u16 tcp_app_hashkey(__be16 port)
605 {
606         return (((__force u16)port >> TCP_APP_TAB_BITS) ^ (__force u16)port)
607                 & TCP_APP_TAB_MASK;
608 }
609 
610 
611 static int tcp_register_app(struct ip_vs_app *inc)
612 {
613         struct ip_vs_app *i;
614         __u16 hash;
615         __be16 port = inc->port;
616         int ret = 0;
617 
618         hash = tcp_app_hashkey(port);
619 
620         spin_lock_bh(&tcp_app_lock);
621         list_for_each_entry(i, &tcp_apps[hash], p_list) {
622                 if (i->port == port) {
623                         ret = -EEXIST;
624                         goto out;
625                 }
626         }
627         list_add(&inc->p_list, &tcp_apps[hash]);
628         atomic_inc(&ip_vs_protocol_tcp.appcnt);
629 
630   out:
631         spin_unlock_bh(&tcp_app_lock);
632         return ret;
633 }
634 
635 
636 static void
637 tcp_unregister_app(struct ip_vs_app *inc)
638 {
639         spin_lock_bh(&tcp_app_lock);
640         atomic_dec(&ip_vs_protocol_tcp.appcnt);
641         list_del(&inc->p_list);
642         spin_unlock_bh(&tcp_app_lock);
643 }
644 
645 
646 static int
647 tcp_app_conn_bind(struct ip_vs_conn *cp)
648 {
649         int hash;
650         struct ip_vs_app *inc;
651         int result = 0;
652 
653         /* Default binding: bind app only for NAT */
654         if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
655                 return 0;
656 
657         /* Lookup application incarnations and bind the right one */
658         hash = tcp_app_hashkey(cp->vport);
659 
660         spin_lock(&tcp_app_lock);
661         list_for_each_entry(inc, &tcp_apps[hash], p_list) {
662                 if (inc->port == cp->vport) {
663                         if (unlikely(!ip_vs_app_inc_get(inc)))
664                                 break;
665                         spin_unlock(&tcp_app_lock);
666 
667                         IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
668                                       "%s:%u to app %s on port %u\n",
669                                       __func__,
670                                       IP_VS_DBG_ADDR(cp->af, &cp->caddr),
671                                       ntohs(cp->cport),
672                                       IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
673                                       ntohs(cp->vport),
674                                       inc->name, ntohs(inc->port));
675 
676                         cp->app = inc;
677                         if (inc->init_conn)
678                                 result = inc->init_conn(inc, cp);
679                         goto out;
680                 }
681         }
682         spin_unlock(&tcp_app_lock);
683 
684   out:
685         return result;
686 }
687 
688 
689 /*
690  *      Set LISTEN timeout. (ip_vs_conn_put will setup timer)
691  */
692 void ip_vs_tcp_conn_listen(struct ip_vs_conn *cp)
693 {
694         spin_lock(&cp->lock);
695         cp->state = IP_VS_TCP_S_LISTEN;
696         cp->timeout = ip_vs_protocol_tcp.timeout_table[IP_VS_TCP_S_LISTEN];
697         spin_unlock(&cp->lock);
698 }
699 
700 
701 static void ip_vs_tcp_init(struct ip_vs_protocol *pp)
702 {
703         IP_VS_INIT_HASH_TABLE(tcp_apps);
704         pp->timeout_table = tcp_timeouts;
705 }
706 
707 
708 static void ip_vs_tcp_exit(struct ip_vs_protocol *pp)
709 {
710 }
711 
712 
713 struct ip_vs_protocol ip_vs_protocol_tcp = {
714         .name =                 "TCP",
715         .protocol =             IPPROTO_TCP,
716         .num_states =           IP_VS_TCP_S_LAST,
717         .dont_defrag =          0,
718         .appcnt =               ATOMIC_INIT(0),
719         .init =                 ip_vs_tcp_init,
720         .exit =                 ip_vs_tcp_exit,
721         .register_app =         tcp_register_app,
722         .unregister_app =       tcp_unregister_app,
723         .conn_schedule =        tcp_conn_schedule,
724         .conn_in_get =          tcp_conn_in_get,
725         .conn_out_get =         tcp_conn_out_get,
726         .snat_handler =         tcp_snat_handler,
727         .dnat_handler =         tcp_dnat_handler,
728         .csum_check =           tcp_csum_check,
729         .state_name =           tcp_state_name,
730         .state_transition =     tcp_state_transition,
731         .app_conn_bind =        tcp_app_conn_bind,
732         .debug_packet =         ip_vs_tcpudp_debug_packet,
733         .timeout_change =       tcp_timeout_change,
734         .set_state_timeout =    tcp_set_state_timeout,
735 };
736 

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